using System;
using System.Text.RegularExpressions;
using System.Linq;
public class Test
{
    public static void Main()
	{
        string[] strings =
        {
            "ABC1100 - 2ppl",
            "ABC1300",
            "ABC 1300",
            "ABC-1300",
            "Managers Associates Only (ABC1100 - 2ppl)"
        };
        
        var reg = new Regex(@"ABC[\s,-]?[0-9]+");
        
        var systemNames = strings.Select(line => reg.Match(line).Value);
        
        systemNames.ToList().ForEach(Console.WriteLine);
	}
}